linux-kernel - Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs and dma changed

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Message-ID: <20161130144105.2b6be4fe@lxorguk.ukuu.org.uk>
Date:   Wed, 30 Nov 2016 14:41:05 +0000
From:   One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:     David Howells <dhowells@...hat.com>
Cc:     minyard@....org, keyrings@...r.kernel.org,
        matthew.garrett@...ula.com, linux-security-module@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Lock down drivers that can have io ports, io mem, irqs
 and dma changed

On Tue, 29 Nov 2016 14:03:31 +0000
David Howells <dhowells@...hat.com> wrote:

> How about the attached?  Obviously it need extending to other drivers.
> 
> I thought that if I'm changing the module_param annotations anyway then it's
> probably worth bunging in an extra parameter that notes what the parameter
> modifies (ioport, iomem, etc.) for future reference, even if we don't store
> it.


With a security hat on the security best practice and long standing
accepted rule is that you whitelist rather than blacklist, so there ought
to be a 

module_param_safe_array()
etc

to mark parameters that are safe, not the reverse.


That debate aside I think the patch is exactly what is needed for this,
and is probably useful for more general hardening as well.

Alan